The present invention relates to an abnormality detection method and protection apparatus and, more particularly, to a technique for detecting any abnormal heating of a device.
Electric devices take various protections against overheat. FIG. 1 shows a typical circuit for detecting any abnormal heating, and FIG. 2 is a flow chart showing its operation.
A determination circuit 2 detects the temperature of a heating member 3 from the output of a temperature sensor 4 attached to the heating member 3 in a device 1 to be protected and monitored (S1). If the circuit 2 detects a temperature that has exceeded a predetermined temperature (S2), it outputs an alarm signal 5 (S3).
For example, Japanese Patent Laid-Open No. 2000-32653 discloses an example in which an element (temperature sensor 4), the resistance of which increases with increasing temperature, and the heating member 3 are arranged adjacent to each other. Japanese Utility Model Laid-Open No. 63-35967 discloses a method of attaching a plurality of temperature sensors at symmetric positions with respect to an object to be monitored, and detecting any abnormal heating based on the difference between the right and left temperatures of the object to be monitored, which are detected by these temperature sensors. Furthermore, Japanese Patent Laid-Open No. 5-60617 discloses a method for measuring the temperature distribution of an object to be monitored using an infrared camera, and detecting any abnormal heating.
The abnormal heating detection method shown in FIGS. 1 and 2, and the methods disclosed in Japanese Patent Laid-Open No. 2000-32653 and Japanese Utility Model Laid-Open No. 63-35967 are limited to specific objects to be monitored, and cannot cope with heating of an object of which overheating is unexpected. That is, it is a common practice to set a temperature sensor in the vicinity of a member, which is expected to generate heat, and to take heating protection when the temperature of that member exceeds a predetermined value. However, abnormal heating of a member which is not expected to generate heat may be neglected.
On the other hand, the method of detecting any abnormal heating from the temperature distribution (Japanese Patent Laid-Open No. 5-60617) does not limit an object to be monitored. However, it is difficult- in terms of hardware and cost to monitor the interior of an electric device used in a house without any dead angles using an infrared camera.
The present invention has been made to solve the aforementioned problems individually or together, and has as its object to detect abnormal heating at an arbitrary position in a device.
In order to achieve the above object, a preferred embodiment of the present invention discloses a method of detecting temperature abnormality of a device, comprising the steps of: acquiring temperature data from a plurality of temperature sensors distributed in the device; acquiring a parameter indicating a temperature distribution pattern in the device on the basis of the acquired temperature data; and outputting, when the acquired parameter deviates from a predetermined parameter indicating a temperature distribution pattern, a signal indicating temperature abnormality of the device.
Also, a preferred embodiment of the present invention discloses a protection apparatus comprising: a plurality of temperature sensors distributed in a device to be protected; an acquisition section, arranged to acquire temperature data from the plurality of temperature sensors, and acquire a parameter indicating a temperature distribution pattern in the device on the basis of the acquired temperature data; and a determiner, arranged to output, when the acquired parameter deviates from a predetermined parameter indicating a temperature distribution pattern, a signal indicating temperature abnormality of the device.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.